No major change in the direction of ongoing studies on leukocytes and platelets have been projected. The soft agar tissue culture technique for the analysis of hematopoietic colonies on the EM level will be used with two goals in mind: 1) the identification of "factors" which induce differentiation of precursor cells into definitive cell types and 2) the analysis of pathologic specimens under similar conditions. Thymus factor (TF) prepared in the laboratory of Dr. J.F. Bach in Paris will be used in these cultures to attempt differentiation of lymphocytes. Mitogen stimulated lymphocytes will be used in feeder layers in the hope of promoting the differentiation of eosinophils. Studies on lymphocytes from patients with Sezary Syndrome and/or mycosis fungoides will concern primarily the possible elucidation of the biochemical composition and function of the cytoplasmic microfibrils we have found in these cells. Work on platelets of patients with thrombocytopenia and myelofibrosis initiated during the past year will continue as planned. BIBLIOGRAPHIC REFERENCES: Zucker-Franklin, D.: Thymus-dependent lymphocytes in lymphoproliferative disorders of the skin. J. Invest. Dermatol., 67:412-418, 1976. Lutas, E.M. and Zucker-Franklin, D.: Formation of lipid inclusions in normal human leukocytes. Blood, In press (Jan. 1977).